Conventionally, ultrasound diagnosis apparatuses acquire three-dimensional data (volume data) by using a two-dimensional (2D) array probe or a mechanical four-dimensional (4D) probe so that users are able to view the inside of a lumen such as the portal vein in the liver or a lactiferous duct by using the acquired volume data. To realize such a viewing of the inside of a lumen, examples of methods being used include a virtual endoscopic display method by which the inside of the lumen is displayed as if the lumen was viewed through an endoscope. In the following explanation, a virtual endoscopic display may be referred to as a Fly Thru display.
To realize the Fly Thru display, a viewpoint and a line-of-sight direction are set on the inside of the lumen contained in volume data, so as to generate and display a perspective projection image (a Perspective Volume Rendering (PVR) image). During a Fly Thru display process, a Fly Thru image is displayed which is a moving image obtained by updating the generated PVR image while moving the viewpoint position along the lumen.
Also, the Fly Thru display makes it possible to view, together with the Fly Thru image, the internal wall of the entire lumen, by generating and displaying Multi-Planar Reconstruction (MPR) images on three cross-sectional planes orthogonal to the line-of-sight direction. However, according to the conventional technique described above, there are some situations where the lumen in a Fly Thru image is not properly displayed.